Hydroxy [di(polyfluorohaloalkyl)] methylmalononitriles, their prpearation, and 1, 1-d(polyfluorohaloalkyl)-2, 2-dicyanoethylenes made therefrom



United States Patent This invention relates to, and has as its principalobjects provision of, a novel and useful class of fluoroalkylsubstitutedcyanoethylenes, novel precursors of these compounds and a method for thepreparation of all of the same.

Fluoroalkyl-substituted cyanoethylenes are a new class of organiccompounds in which the structural features of cyanocarbon olefins andfluorocarbon olefins are combined. This combination results in usefulchemical properties that are traceable to either cyanocarbons orfluorocarbons and also in some unusual specific properties that arenarrowly characteristic of specific structures Within the class and areentirely unpredictable.

It has now been discovered that the previously unknown 1,1di(polyfiuorohaloalkyl)-2,2-dicyanoethylencs (II) can be prepared bydehydration of hydroxy[di(polyfluorohaloalkyD]methylmalononitriles (I),also novel compounds which in turn are prepared by reactingmalononitrile with polyfiuorohaloalkyl ketones. New products of theinvention and the methods of making them are illustrated by thefollowing equations:

( R 0N R 0 2 6:0 HJIH HO-( ]H I l N R ON and (B) R ON R CN HO )-lH H20 Ii. lN R CN Here Formula I represents the hydroxy[di(polyiluorohaloalkyl)]methylmalononitriles and Formula II represents the 1,1di(polyfiuorohaloalkyl)-2,2-dicyanoethylenes. In all formulae R andRare, separately the same or different monovalent polyfluorohaloalkylgroups, including w-hydroperfluoroalkyl, w-haloperfluoroalkyl anderfiuoroalkyl groups, or, conjointly, a divalent perfluoroalkylenegroup.

Preferred compounds of the invention are those in which separate R and Rgroups have up to 18 carbon atoms or in which conjoined R and R groupsform a perfiuoroalkylene group of 3 to 5 carbon atoms. Especiallypreferred products are those in which separate R and R groups eachcontain up to 8 carbon atoms.

As noted in Equation A, the hydroxy[di(polyfluorohaloalkyl)jmethylmalononitriles (I) can be prepared, and readily, frommalononitrile and polyfiuorohaloalkyl ketones. The reaction of theketone and malononitrile is conveniently carried out in the presence ofzinc chloride as catalyst at a temperature in the range of about 50 toabout 150 C. The resultant hydroxy compound is usual- 1y a crystallinesolid which can be isolated and purified in a conventional manner, orwhich may be used directly (without purification) in the dehydrationreaction to form the corresponding 1,l-di(polyfluorohaloalkyl)-2,2-dicyanoethylene.

Dehydration of a hydroxy[di(polyfluorohal0alkyl)] methylmalononitrile(I) as by Equation B is readily accomplished by heating the same,preferably in the presence of a water acceptor, i.e., a substance thatwill react with or otherwise retain water. A dehydrating agent such asphosphorus pentoxide is of particular advantage as a water acceptor, andwith use of such a dehydrating agent the product is convenientlyseparated as it is formed by distillation from the reaction vessel.Alternatively, the dehydration can be carried out in a vapor phaseprocess in which the vaporized hydroxy compound is passed through aporous layer of a solid water acceptor, e.g., silica gel. Thedehydration can also be accomplished by heating the hydroxy compound inthe absence of a water acceptor, but since the dehydration reaction isreversible this method of operation is impractical unless an alternativemethod of separating the water from the ethylenic compound is used,e.g., fractional distillation.

The temperature of dehydration is generally above about 169 C., and whenthe product is removed by distillation the reaction temperature will besomewhat above the boiling point of the product. However, thetemperature of dehydration is not critical and can be quite high, e.g.above 300 C., since the 1,1-di(polyfiuorohaloalkyl)- 2,2-dicyanoethyleneproducts are thermally stable.

The 1,1-di(fiuoroalkyl) 2,2 dicyanoethylenes, being ethylenes having apreponderance of highly negative substituents on the carbons attached tothe double bond, are relatively strong 1r-acids that can form coloredcomplexes with aromatic hydrocarbon tr-bases. In this property they arelike the 1,2-di(fluoroalkyl)-1,2-dicyanoethy1enes, new compoundsdescribed in US. Patent No. 3,133,115 of May 12, 1964. However, unlikethe isomeric 1,2-di(fluoroalkyl)-1,2-dicyanoethylenes, the1,1-di(fluoroalkyl)-2, Z-dicyanoethylenes of this invention areadditionally and unexpectedly characterized by their readiness to reactwith activated aromatic nuclei, e.g. the benzene ring in aniline, and toundergo cycloaddition with electron-rich olefinic compounds, e.g.,styrene. Furthermore, the 1,1-(difluoroalkyl)-2,2-dicyanoethylenes andthe 1,2-(difluoroalkyl)- 1,2-dicyanoethylenes are most advantageouslyprepared by completely different processes.

The invention is illustrated in greater detail in the followingexamples.

EXAMPLE I A. H ydroxy-bz's( trifluoromethyl methylmalononitrile CF3 ON FON A mixture of g. (1.14 g. mole) of malononitrile, 4 g. (0.03 g. mole)of anhydrous zinc chloride and 150 g. (0.9 g. mole) of hexafluoroacetonewas heated in a 240 ml. pressure vessel at C. for 8 hours. An oft-whitecrystalline solid, 211 g., was obtained after the reactor was cooled andvented. A sample of the solid was recrystallized from methylene chlorideto give hydroXy-bis(trifiuoromethyl)methylmalononitrile as hygroscopicwhite needles, MP. 597() C.

Anal. for C H F N OI TABLE I 1 C i 11 i F N Fluoroalkyl Ketone1,l-Di(fluoroalkyl)-2,2-dicyanoethyleue Calcd 31.0 0.87 49.1 1 .1 5 O tflu r 1 ntanon D a in th l H o nd n 31.5 1' 501 14.4 G a 0 CW1 p 0 glrlel 0 yencocm uvrocyclopen DecafiuorocyelohexanoneDieyanomethylenedecafluorocycloe yene.

OF; CN CF ON I I or. KIJN or. CN

A mixture of 211 g. (0.9 g. mole) of crudehydroxybis(trifluoromethyl)methylmalononitrile, prepared as in Part Afrom 75 g. of malononitrile and 150 g. of hexafluoroactone, and 454 g.(3.2 g. mole) of phosphorus pentoxide was heated strongly in a 5 literflask connected to a simple still until no further distillate wascollected. The distillate was filtered and redistilled to give 97 g. of1,1-bis(trifluoromethyl)-2,2-dicyanoethylene: B.P. 107; 11 1.3526; D1.479. The n-m-r fluorine spectrum contained a single unsplit resonanceband. The infrared spectrum contained characterizing absorption bands at4.45 m (forCN) and 6.1 mg (for C=C).

Anal. for C F N A mixture of malonitrile 14.4 g. (0.02 g. mole) 1 g.(0.007 g. mole) of zincchloride and 36 g. (0.2 g. mole) ofhexafluorocyclobutanone were sealed in a 130 ml. Carius tube and heatedto 50 C. for 2 hours. The tube .was cooled, opened and vented. Thereaction mixture was a fluid semi-solid.

B. Dicyanomethylenehexafluorocyclobutane OH CN CN I P205 l CF2C 11(JIM-(3:0 H20 JF F JIN CFrCFz ON Anal. for C F N I C i F Calc'd 37.2 50.5 Found 37. 50.3

Inthe manner of the foregoing examples a large number of1,1-di(polyfluorohaloalkyl)-2,2-dicyanoethylenes can be obtained byreaction of malononitrile with fluoroalkyl ketones and subsequentdehydration of the hydroxy[di (polyfluorohaloalkyl)]methyl1nalononitriles thus formed. In the following table are listedrepresentative 1,1-di(polyfiuorohaloalkyl)-2,2-dicyanoethylenes and thepolyfluorohaloalkyl ketones from which they are derived.

Decafluoro-Z-pentanone l-Heptafiuoropropyl-l-trilluoromethyl-2,2-dicyanoethylene.

1,1-D1(perfluoroheptyl)-2,2-dieyanoethylene.

l-lerfiuorornethyl-l-perfluoroheptadecy1-2,2-dicyanoethylene.

Perlluoro-B-deeauone Perlluoro-8-pentadeeanone.

Perfluoro-Z-nonadeeanone Perfluoro-18-pentatriaeontanone.1,3-Diehloro-1,1,3,3-tetratlu0ro- 1,1-Bis (ehlorodifluoromethyl) -2,2-2-propanone. dicyanoethylenc. 1,Q-Diehloropertluoro-S-nona- 1,1-B is(4-chloroperfluorobutyl) -2,2-

none. dieyanoethylene. 1,13-Dichloroperfiuoro-7-tri- 1,1-B is(ts-ehloroperfluorohexyl) -2,2-

deeauone. dieyauoethylene. 1,3-Dibrom0-1,l,3,3-tetra-1,1-Bis(bromodifiuoromethyl)-2,2-

fiuoro-Z-propanone. dieyanoethylene.

l-Difluoromethyl-l-trifiuoromethyl- 2.2-dieyanoetliylene.

1,1-Bis (difluoromethyl)-2,2; licyano ethylene.

1,1-Bis (IZH-perlluorodeeyl)'2,2-dicyanoethylene.

none. 1H,25H-perfiuoro-13-pentacosanone.

The 1,1 di(polyfluorohaloalkyl)-2,2-dicyanoethylenes shown in theexamples and in Table I have various utilities, some of which areillustrated in Examples A, B and C, below.

EXAMPLE A The novel 1, 1 -di (polyfluorohaloalkyl -2,2-dicyanoethylenesof this invention are 1r-E1C1C1S which form characteristic coloredcomplexes with aromatic compounds (i.c., wr-bElSBS) and thus can be usedin the analytical detection and estimation of such compounds. The basisfor this use is illustrated in Table II, which shows the wavelength ofmaximum absorption [A max., cf. Keefer et al., J. Am. Chem. Soc. 72,4677 (1950)] in methylene chloride of w-complexes formed by the productsof Examples I-B and II-B with representative aromatic hydrocarbonrr-bfiSES.

TAB LE II Tr-BESG max., m

EXAMPLE B The 1,1 di(polyfluorohaloalkyl)-2,2-dicyanoethylenes alsoreact readily with activated aromatic nuclei, and thus are useful asintermediates in the preparation of nuclear-substituted aromaticcompounds. For example, p-[fl,5dicyano-a,a-bis(trifluoromethyl)ethyl]aniline was obtained in thereaction:

A solution of 0.93 g. (0.01 g. mole) of aniline in 5 ml. of ether wasadded dropwise to a stirred and cooled solution of 2.14 g. (0.01 g.mole) of 1,l-bis(trifluoromethyl)- 2,2-dicyanoethylene in 10 ml. ofether. The reaction mixture was filtered, and the filtrate wasevaporated to dryness. The solid residue was recrystallized from hexaneto give 1.58 g. ofp-[{3,fl-dicyano-a,ot-bis(tritluoromethyl)ethyl]aniline as colorlessneedles, M.P. 107 C.

The product was found to be insoluble in water but soluble in dilutehydrochloric acid or sodium hydroxide. The n-m-r and infrared spectrawas consistent with the p-substituted aniline structure.

first formed faded rapidly, and the white crystalline precipitate thatformed was collected on a filter and washed with pentane.Recrystallization from pentane gave 5.55 g. of1,1-dicyano-2-phenyl-4,4-bis(trifluorornethyl) cyclobu- Anal. for C H FN 5 tane as colorless prisms, MP. 77 to 78 C.

Anal. for C H F N C H F N C H F N Calcd 4s. 9 2. 30 37.1 13. 7 Found 4M3&0 Calod 52.8 2.54 35.8 8.8 Found 53.9 3. 01 35.2 8.4 A solution of 0.1g. of sodium nitrite in 5 ml. of water was added to a cooled solution of0.1 g. of the p-[Bfi- In these reactions with styrene andu-methylstyrene 1,1- dicyano-a,a-bis(trilluoromethyDethylJaniline in 5ml. 9f bis(trifiuorornethyl)-2,2-dicyanoethylene is again unpredilutehydrochloric acid. ,B-naphthol, 0.1 g., was then 15 dictably differentfrom its isomer, 1,2-bis(trifiuoromethstirred with the reaction productand 5% sodium hydroxyl)-l,2-dicyanoethylene, since substitution of thelatter for ide was added until the solution became homogeneous theformer in the above-described process produced no and brilliant orange.A piece of wool fabric was dyed evidence of any reaction. orange byimmersing it in the solution for 1 min. and then Since obviousmodifications and equivalents in the inthoroughly washing it with soapand water. vention will be evident to those skilled in the chemical Inthis reaction 1,1-bis (trifluoroinethyl)-2,2-dicyano- 7 arts, I proposeto be bound solely by the appended claims. ethylene is unpredictablydifferent from the isomeric cone The embodiments of the invention inwhich an exclupound, l,2-bis(trifluoromethyl)-1,2-dicyanoethylene,since. sive property or privilege is claimed are defined as folthelatter did not react with aniline in the same manner. lows:

EXAMPLE 0 I 1. 1,l-d1(polyfiuorohaloalkyl) 2,2 dicyanoethylenes ravingthe formula Another useful property of the 1,1-di(polyfluorohalo- R 0Nalkyl)-2,2-dicyanoethy1enes is their unusual readiness to I undergocycloaddition with electron-rich olefinic compounds to formcyclobutanes. This property is exempli- CN fied in the followingreactions that have been carried out wherein R and are selected,individually, f the at low temperature wlth styrene and a-methylstyrene.group c nSis ing f hydroperfiuoroalky1 d -1131013512- CN CFQ fiuoroalkylof up to 18 carbons and, jointly, of perfiuoroalkylene of between 3 and5 carbons. (13:0 2. 1,1-bis(trifiuoromethyl)-2,2-dicyanoethylene.

0 (m 3. Dicyanornethylenehexafiuorocyclobutane.

NC 4. Hydroxy[di(polyfluorohaloalkyl)Jmethylrnalononi- 0 CFS trileshaving the formula 0113 ON 01% on. f E =cHz+ :2 -CH HO(|}CH (3N r3 l NC(I3 G OF3 wherein R and R are selected, individually, from the CN F3group consisting of w-hydroperfluoroall y1 and w-haloper- CH ON CFfiuoroalkyl of up to 18 carbons and, jointly, of perfiuoro- 3 I alkyleneof between 3 and 5 carbons. Q 2 9:0 5.HydroXy-bis(trifluorornethyl)methylmalononitrile. 6.(l-hydroxyhexafluoro-l-cyclobutyl)malononitrile.

CH2 7. The process of producing a hydroxy[di(polyiiuoro- Ihaloalkyl)Jmethylrnalonitrile which comprises reacting I malononitrileand a polyfluorohaloalkyl ketone at a temperature of about 50-150 C. andin the presence of zinc chloride.

N CFz-CFZ 8. The process of producinghydroxy-bis(trifluoroniethyDmethylmalonouitrile which comprises reactingmalonoi Struclures of i cyclobutalles formed not known nitrile andhexafluoroacetone at a temperature of about with certalnty, thelllustrated assignments being based on 504500 C and in the a p hlpresence or zinc c onde. me exgspted l p i of 1.16 olefin? andthe.dlrectl.on 9. The process of producing (l-hydroxyhexafluoro-I- ofaddrtlon established 1n their reversible reactions with socyclobutynmalononitrfle which Comprises reacting AS exam? the reilcnonof lononitrile and perfluorocyclobutanone atatemperature of 35233;' Wlthstyrene 1s detalled as about 50-150 C. and in the presence of zincchloride.

A solution of 2.08 g. (0.02 g.l mole) of styrene in g 1111- ReferencesCited in the file of this patent of pentane was added to a so utlon of.28 (0. 2 g. UNITED STATES PATENTS mole) of 1, l-bis(trifluoromethyl)-2,2-dicyanoethylene in 5 ml. of pentane cooled to 0 C.The deep yellow color that 2,541,466 Dickey Feb. 13, 1951

1. 1,1-DI(POLYFLUOROHALOALKYL) -2,2 - DICYANOETHYLENES HAVING THEFORMULA
 4. HYDROXY (DI(POLYFLUOROHALOALKYL)(METHYLMALONONITRILES HAVINGTHE FORMULA